1. Field of the Invention
The present invention relates to a semiconductor device and its manufacturing method, to a stacked structure including the semiconductor device, and to a package including the stacked structure.
2. Description of the Related Art
Multichip semiconductor devices in which a plurality of semiconductor chips are stacked in various ways are under development for the twin purposes of greater functionality and greater integration. One example is described in Japanese Patent Application Publication No. 10-223833, which discloses a semiconductor device comprising a stack of semiconductor integrated circuit chips interconnected by plugs and bumps.
In this structure, the heat generated by the integrated circuit chips is to some extent dissipated to the ambient environment through the interconnecting plugs, but this heat dissipation mechanism is inadequate. In particular, there is no path for dissipation of heat generated near the center of the multichip device. The device therefore has a tendency to overheat, particularly in its central regions.
When the stacked structure forms a stacked multichip package, as the temperature within the package rises, there is a risk of thermal damage to the circuit elements in the constituent integrated circuit chips, thermal distortion of the multichip package as a whole, and thermal distortion of its structural elements. High temperatures can also cause semiconductor circuits to operate incorrectly, even if they are not permanently distorted or damaged. The ultimate result is that stacked semiconductor devices and in particular stacked multichip packages are unreliable.
There is an urgent need for technology to improve the heat dissipation performance of stacked multichip packages, and for a simplified way to manufacture the semiconductor devices constituting the stack so as to have improved heat dissipation properties.